He also won a race at the Hungaroring to finish third in the series standings, missing out on the runner-up placing by just one point to Artur Janosz.

At the Circuit de Barcelona-Catalunya in Spain,[6] Palou qualified fourth for the first race, but he slipped the clutch at the start and lost any opportunity to fight for the points.

He made "The Great Mistake" (as he wrote in his column) when during the warm-up lap he spun at the main straight and nearly hit the wall.

At the Sochi Autodrom in Russia,[12] Palou received a new engine that solved the top speed problems he suffered in Belgium and Italy.

Because of Carlos Sainz's crash during Russian Grand Prix Free Practice 3, the first race of the weekend was moved to Sunday.

Palou qualified just a tenth away from Pole Position and scored a provisional season-high in the first race when he crossed the line in fourth place.

He started from fourth, but during the warm-up lap a gas sensor failed and the car kept on accelerating when the driver lifted the throttle.

At the Yas Marina Circuit in Abu Dhabi,[14] Palou won his race in GP3 and became the first Spanish driver to ever get a victory in the series.

Palou led the majority of the Jerez sprint race from the reverse grid pole, but ultimately, he could not hang on to the lead with his heavily worn tires and finished 8th.

In 2018, Palou returned to Europe full-time for a full season with Hitech Bullfrog GP in the 2018 FIA Formula 3 European Championship.

[15] On 19 December 2019, it was announced that Palou would move to the IndyCar Series for a rookie campaign with Dale Coyne Racing with Team Goh.

[18] On 18 April 2021, Palou earned his maiden IndyCar Series victory in the season-opening race at Barber Motorsports Park.

[19] Palou added another podium for the season at the GMR Grand Prix and then finished second in the 2021 Indianapolis 500 to Hélio Castroneves' record-tying fourth victory.

He gave up the points lead to O'Ward after he and Dixon were collected in an accident caused by Rinus VeeKay at Gateway but took it back after taking his first earned pole position and a third victory at Portland.

After O'Ward was knocked out in an accident on the first lap of the race Palou drove conservatively and finished in fourth place, winning his first IndyCar championship.

[21] Palou also secured his first IndyCar track discipline championship in 2021, winning the Mario Andretti Cup as the season's highest-scoring driver on the road and street courses.

For his Indianapolis Motor Speedway victory lap, he drove a chicken-themed limousine, in honor of his favorite after-victory meal of fried chicken.

[22] Palou would start the 2022 season out with podiums at St. Petersburg, Long Beach, and Barber, outperforming his Chip Ganassi teammates and putting him in a strong early position to defend his title.

[23][24] The title would eventually be lost to Penske's Will Power, but Palou would still finish 5th (due to countback, as he tied Scott McLaughlin with 510 points) with a commanding win in the Laguna Seca finale to round out the year.

On 12 July 2022, Chip Ganassi Racing sent a press release saying that they had extended the contract of Palou for the 2023 IndyCar season by exercising the option they held on his deal.

[28] On 27 July 2022, Chip Ganassi Racing confirmed they had filed a civil lawsuit against Palou in Marion County, Indiana.

[36] Palou started his season strongly, picking up top five finishes in four of the first five races and winning the GMR Grand Prix leading up to the 107th Indianapolis 500.

[37] Palou took his second victory of the season at the Detroit Grand Prix,[38] and then won again at the following round in Road America, followed by a third consecutive win at Mid-Ohio.